1. Field of the Invention
The present invention relates to a crossbar switch mounted on a computer, for example, for image processing, and to a product associated therewith.
2. Description of the Related Art
A crossbar switch is a system component for realizing, with few limitations, the node coupling in a multiprocessor. Typical crossbar switches have a plurality of buses arranged in the form of a two-dimensional grid. Switch mechanisms are disposed in each of a plurality of intersection points (called “cross points”) where buses intersect with each other. At the time of operation, a data path defined by a combination of certain portions of buses and cross points between node-in lines (buses for the data input to each node) and node-out lines (buses for the data output from each node) can be selectively switched by controlling connection/disconnection of cross points with switch mechanisms.
Advantages of the crossbar switch are in excellent non-blocking ability preventing collisions between the data and a comparatively simple structure and control thereof. For this reason, they are used in many data processing devices.
It is well-known that the structure of the conventional crossbar switch requires that the number of switch mechanisms be a square of the number of nodes. Furthermore, in the case of parallel connections, an additional circuit element such as an input buffer or arbiter for each bus has to be provided to avoid the problem of competition between the output lines. For this reason, the size of the crossbar switch was difficult to reduce.
For example, in a crossbar switch of a configuration switching 256 to 1024 nodes, the number of cross points is 64 kilopoints to 1 megapoints. If the bus width of a parallel bus is 32 bits, then the number of switches is maximum 32 megaunits. Configuring and mounting such a large-scale system on a small area is extremely difficult with present process rules. Furthermore, with the conventional configuration of crossbar switches, not only the switch control during changeover processing of data paths becomes more complex as the number of switches increases, but also the number of lines for switch control rapidly increases.
The present invention was made to solve the above-mentioned problems, and it is an object of the present invention to provide a small cost-effective crossbar switch, without increasing the number of lines and without increasing the complexity of switch control during changeover processing of data paths, even when the number of switches is increased, and to provide a product associated therewith.